Density of materials and the particle model of matter
Methods of measuring density - list
of densities of common materials
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A simple experiment to determine the density of a
material is described, and how to use the formula for density to calculate
density. This section also looks at density from the point of view
of a particle model of matter. In everyday language, dense objects are described as
'heavy' and less dense objects as 'light', but this is not a correct scientific
description of the object or the nature of the material.
Sub-index for this page
1.
What is density? What is the
formula for density?
2.
Why is density data important? Examples of densities
3.
Experiments to determine the density of a material
3a.
Measuring the density of an irregularly shaped
solid object and calculations
3b.
Measuring the density of an regular shaped
solid object and calculations
3c.
Three ways of
measuring the density of a liquid and calculations
4.
Calculations involving density
5.
Density
and particle model
- explaining the relative densities of gases, liquids, solids
6.
The relative density of the liquid and
solid state and the curious case of water
7.
Thermal expansion and density
Density is also mentioned in
Pressure & upthrust in liquids, density and why do
objects float or sink?
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1.
What is density? What is the formula for density?
Density is a measure of how compact a
material is - it indicates how much space or volume a given mass occupies.
The greater the mass of material in a given
volume, the greater the density of the material.
The density of a material depends on what it
is made up of (atoms and their arrangement) and its physical state.
The more spread out the particles, the
lower the material's density - which is why gases have a very low density.
The more closely the particles are packed
together, the greater the density - which is why solids have the highest
density.
See the
particle model of the states of
matter
The density for a given material is the same
whatever its shape or size for a given physical state.
The
scientific symbol for density is the Greek letter rho (ρ)
The formula for density is:
ρ
= m
÷ v
DENSITY (kg/m3)
= MASS (kg)
÷
VOLUME (m3)
Density units in physics are usually kg/m3.
However, in chemistry, density data is often
quoted in g/cm3 because most quantitative measurements in a
school/college chemistry laboratory are usually quoted in grams (g) and ml (cm3),
so I've sometimes quoted both sets of units,
so don't get them muddled! and note that:
g/cm3 = kg/m3
÷ 1000 (can you
work out why?)
Its advisable to be able to convert mass
and volume units e.g.
mass: 1 kilogram = 1000 grams, so:
g ÷ 1000 = kg and kg x 1000 = g
volume: ml = cm3, 1
cubic metre = 1 million cm3, so: cm3 ÷
106 = m3 and m3
x 106 = cm3
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2. Why is density data important? Examples of densities
Density is very important property to know about a material
e.g. if the density of an object is less
than that of water (~1000 kg/m3) it floats.
If the density of an object is more
than that of water it sinks!
In general: if the object has a
density < fluid it floats and if density of object is > fluid it sinks.
However, although shape doesn't
affect density, shape does affect flotation on non-flotation, otherwise, how can a steel ship float on
water!?
Examples of density in kg/m3
(at ~room temperature, 20oC)
The table lists the densities of many
common materials, all of them are useful materials for some application
or other.
Note that
gases are so much less dense
than liquids or solids. - refer to
particle model.
Material |
Density |
Comments |
hydrogen |
0.09 |
The
element H, least dense material, 'floats' in less dense air |
helium |
0.18 |
The
element He, next least dense material, 'floats' in less
dense air - balloons |
air |
1.3 |
Mainly
nitrogen N2 and oxygen O2 molecules. |
carbon dioxide |
1.9 |
|
cork |
240 |
|
wood |
380 - 700 |
Important construction material |
solid paraffin wax |
720 |
|
petrol |
710 - 770 |
Important fuel |
crude oil |
840 - 970 |
Variable composition of hydrocarbons, floats on water -
polluting oil spills |
ice |
920 |
Floats
on water, less dense than water. |
water |
1000 |
Useful
solvent, transferring thermal energy in central heating
systems |
seawater |
1030 |
More
dense than pure water, you float more easily! |
rubber |
1520 |
Useful
material for flexible joints or shock absorbers. |
brick |
1920 |
Important construction material |
concrete |
2370 |
Important construction material. |
glass |
2580 |
Important construction material |
marble rock |
2560 |
Mainly
calcium carbonate CaCO3, useful for sculptures,
kitchen work tops |
quartz rock |
2640 |
Mainly
silicon dioxide, silica, SiO2, useful for kitchen
worktops |
aluminium |
2640 |
Important metal, used for light alloys - aircraft
construction |
bromine |
3120 |
One of
only two liquid elements at room temperature |
iron |
7500 |
The
element Fe, cast iron has many uses - we experience as
'heavy' objects! |
steel |
7900 |
Mainly
Fe, with added elements, important construction material. |
copper |
8800 |
Copper
wiring and piping. |
lead |
11340 |
'Heavy' metallic element, used in lead roofing |
mercury |
13600 |
One of
only two liquid elements at room temperature |
gold
|
19300 |
Very
dense important metal in jewellery |
osmium |
2260 |
The
most dense element in the periodic table |
All is explained in the section in
Forces section 7. 'floating
and sinking'
TOP OF PAGE and
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3.
Experiments to determine the density of a material
All the apparatus needed for the different
methods for measuring density is described below and illustrated in one big
diagram via parts (1a), (1b),
(2a) and (2b)
on the diagram.
By some means you need to know a
specific mass and volume of a material to calculate its density.
You need to relate the methods described
to the picture diagram, which I've repeated a few times.
Simple experiments to measure the density of a solid material
3a. Measuring the density of an irregularly shaped
solid object and calculation
Any lump of a solid material can be
accurately weighed on an electronic balance (2b)
on the diagram above
(usually grams, g).
Don't forget to tare the mass
balance to zero before placing the object on it.
If the solid is a lump with an irregular
shape (and insoluble in water!) you can use a Eureka can (displacement can)
to measure its volume.
The
eureka can
(1a) on
diagram,
is filled with water above the spout and any excess drains off into the
measuring cylinder so that the water level is just under the spout.
Then empty the collection measuring
cylinder and place it under the spout again.
You then carefully lower the object,
attached to a very fine thread, into
the water.
As the object enters the water, the water
level rises and a volume of water equal to the volume of the object is
displaced from the eureka can down the spout and measured on collection in
the measuring cylinder (1b)
on diagram.
Only measure the volume when the spout
has stopped dripping, otherwise you won't measure the correct volume!
You cannot use this method if the object
has a density <1.0 g/cm3 (1000 kg/m3), because it
floats on water and only partially displaces the water. Repeat several times
and calculate the average volume measured.
Then apply the density formula:
ρ
= m
÷ v
3b. Measuring the density of an regular shaped
solid object and calculation
Again the block of material is weighed on
the electronic balance (2b)
on diagram.
If the material is a perfectly shaped
cube or rectangular block (solid cuboid), you can then accurately measure
the length, breadth and height and calculate the volume:
V = l x b x h.
If it is a regular solid shaped cylinder
you need to work out the surface area of the end and multiply this by the
length or height of the cylinder.
Area of a circle = πr2, where π
= pi = 3.142 and r = radius of the cylinder.
Therefore volume of cylinder: V = πr2l
Then apply the density formula:
ρ
= m
÷ v
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3c.
Three simple experiments to
determine the density of a liquid and calculations
To measure the density of liquid you need to
weighed an accurately measured volume of the liquid.
(i)
Measuring the density of a liquid using a measuring cylinder (2b)
on diagram
If you are only using 10 ml of liquid,
you should use a 10 ml measuring cylinder , a 50 ml measuring cylinder would
not be accurate enough.
A clean empty measuring cylinder is
weighed on the electronic balance (m1).
The liquid under investigation is poured
to a convenient volume v eg 50 cm3 (in a 50 ml measuring
cylinder for best accuracy)
Make sure the bottom of the liquid's
meniscus rests exactly on the 50 cm3 mark.
The measuring cylinder and liquid are
then reweighed (m2).
The difference between the weights gives
you the mass m of the liquid (m = m2 - m1)
density of liquid ρ
= m ÷ v
This is not a very accurate method,
the measuring cylinder is not calibrated to a high standard.
(ii)
Measuring the density of a liquid using a burette or pipette
(both more accurate than a measuring cylinder)
(2a)
and (2b) on diagram
Weigh a suitable container, eg a conical
flask or beaker, on the electronic balance (m1).
Carefully measure into the container an
accurately known volume v of the liquid under investigation.
You can use a burette (for any volume
from 10 to 50 cm3) or a 25 ml (25 cm3) pipette.
In either case make sure the bottom of
the liquid's meniscus rests exactly on the calibration mark for selected
volume.
The container and liquid are reweighed
(m2) and the difference in weight is the mass m of the liquid (m = m2
- m1)
density of liquid ρ
= m ÷ v
This is a more accurate method than
(i), a pipette or burette are calibrated to a higher standard than a
measuring cylinder.
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(iii) Measuring the relative density of a
liquid using a density bottle
The liquid must not be too viscous (too
sticky to run freely).
A density bottle is a glass chamber with
a ground neck entrance. Into the neck goes a precisely fitting stopper with
a capillary tube running down its central axis - see diagrams above. Its
volume can be as little as 10-20 cm3 (10 ml).
Procedure
You need to do the experiment at a
constant temperature because liquids expand/contract if heated/cooled i.e.
density is temperature dependent.
Diagram (3a)
The density bottle and stopper must be completely empty and dried in an
oven before use - obviously must be allowed to cool down to room
temperature at ~25oC.
The density bottle and stopper
are then weighed on a mass balance, preferably to
± 0.01 g (m1)
Diagram (3b)
The density bottle is then completely filled with pure water and the
stopper pushed down to expel any excess water.
With a tissue of filter paper,
any excess fluid on the top of the stopper should be carefully
removed.
You should also make sure there
is no spilt liquid on the outside of the bottle, if so, this should
be carefully wiped off too.
In other words, all the exterior
of the density bottle and stopper must be dry.
Also make sure you don't absorb
any liquid from the capillary tube of the stopper.
Diagram (3c)
The filled density bottle of water is then reweighed on the mass balance
(m2).
Diagram (3d)
The steps from 3a to 3c are then repeated and the final mass of the
bottle/stopper filled is measured (m3).
Results (fiction!)
m1 = mass of empty bottle +
stopper = 35.51 g
m2 = mass of empty bottle +
stopper + water = 50.62 g
m3 = mass of empty bottle +
stopper + liquid X = 48.42 g
Calculation
You can get the accurate density of pure
water from a data table on the internet e.g.
temperature |
10oC |
20oC |
30oC |
density g/cm3 |
0.9997 |
0.9982 |
0.9957 |
density kg/m3 |
999.7 |
998.2 |
995.7 |
(Note: g/cm3 x 1000 = kg/m3)
However, as you can see, by assuming the
density of water is 1.00 g/cm3 (1000 kg/m3), at 20oC
you only introduce a 0.2% error.
(1.00 - 0.998)/1.00) x 100},
for a school/college laboratory,
that's a pretty good accuracy for doing any real experiment.
Assuming constant temperature and
therefore constant volume, the calculation is as follows.
m2 - m1 = mass of water = m4 = 50.62
- 35.51 = 15.11 g of water
m3 - m1 = mass of liquid X = m5 =
48.42 - 35.51 = 12.91 g of liquid X
Density of liquid
ρwater
= mwater
÷ vwater,
v = m ÷ ρ
Therefore
volume of bottle = volume of water = mass of water
÷ density of water
= 15.11
÷ 1.00 = 15.11 cm3
We can now calculate the density
of liquid X.
Density of liquid
X ρX
= mX ÷ vX
= mass of liquid X ÷ volume of liquid X
= 12.91 ÷ 15.11 =
0.854 g/cm3
(x 1000 =
854 kg/m3)
Source of errors
Not ensuring there is no excess
liquid on the outside of the density bottle or on the top of the
stopper.
Not ensuring the bottle is completely dry and empty
before use.
Not ensuring all measurements are
done at the same recorded temperature.
Again, this
again is much more accurate than method (i) and probably more
accurate than method (ii) - too, because you are calibrating the density bottle to a
high standard of accuracy.
To calculate the density of liquid is no
different from the calculations for a solid so I don't feel the need to add any
more density calculations.
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4. Calculations involving density
Q1
Irregular shaped solid object
A stone weighing 27.2 g displaced 8.5 cm3
of water (8.5 ml), calculate its density.
density of solid
ρ
= m ÷ v,
ρ = 27.2 ÷ 8.5 =
3.2 g/cm3
However, you may have to calculate the
density in kg/m3 and this is arithmetically a bit more awkward!
27.2 g = 27.2/1000 = 0.0272 kg
and 8.5 cm3 = 8.5 / 106 = 8.5 x 10-6
m3 (1 m3 = 106 cm3)
ρ
= m ÷ v,
ρ = 0.0272 ÷
(8.5 x 10-6) = 0.0272 ÷ 0.0000085 =
3200 kg/m3
It might be handy to know that kg/m3
is 1000 x g/cm3 !!! 3.2 x 1000 = 3200 !!!
Q2 A regular
solid block
A block of iron had dimensions of 3.0 cm
x 5.0 cm x 12.0 cm and weighed 1.420 kg, calculate the density of iron.
Volume of block = 3 x 5 x 12 = 180 cm3,
volume = 180/106 = 1.8 x 10-4 m3
(0.00018)
density of solid
ρ
= m ÷ v,
ρ = 1.42 ÷
0.00018 = 7889
kg/m3
Q3 A
regular solid cylinder of an alloy has a diameter of 3.0 cm, a length of 12.0 cm
and a mass of 750 g.
Calculate the density in kg/m3
radius of cylinder = diameter/2 = 3.0/2 = 1.5 cm,
cross-section area = πr2 =
3.142 x 1.52 = 7.070 cm2
volume of cylinder = 7.070 x 12.0 = 84.83
cm3, 84.83/106 = 8.483 x 10-5 m3
(remember 1 m3 = 106 cm3)
mass of cylinder = 750/1000 = 0.750 kg
(1 kg = 1000 g)
density of solid
ρ
= m ÷ v,
ρ = 0.750 ÷
8.483 x 10-5 = 8841 =
8840 kg/m3 (3 sf)
Q4
A cube of material
has a side length of 2.5 cm.
If the material has a density of 5000
kg/m3, what is the mass of the cube in g and kg?
l = 2.5/100 = 0.025 m, therefore volume =
l3 = 0.0253 = 1.5625 x 10-5 m3
ρ
= m ÷ v, m =
ρ x v = 5000 x 1.5625 x 10-5
=
0.078 kg (x 1000 =
78 g)
Q5
If the density of air is 1.30 kg/m3
(a) Calculate the mass of air in a room
measuring 7 m by 6 m by 3 m.
Volume of room = l x b x h = 7 x 6 x
3 = 126 m3
ρ
= m ÷ v, m = ρ x v = 1.3 x
126 = 164 kg
(3 sf)
(b) Explain what happens
to the density of air in the room if the atmospheric pressure increases.
If the pressure
increases, on average, the particles are squashed closer together.
Therefore, there is
more mass in the same volume, so the density increases.
Note: (i) The mass
of air in the room will also increase.
(ii) In any
situation where a gas is compressed, the density of the gas is
increased.
Q6
Steel has been cast into long rectangular bars 25 metres long and a
cross-section of 20 cm by 30 cm.
If the density of steel is 7900 kg/m3,
what is the minimum number of bars needed to transport at least 230 tonnes
of the steel?
V = l x b x h, l = 25 m, b = 20/100 = 0.2
m, h = 30/100 = 0.3 m
V of 1 rod = 1.5 m3
ρ
= m ÷ v, m = ρ x v
mass of 1 bar = 7900 x
1.5 = 11850 kg.
230 tonnes
≡
230 000 kg (1 metric tonne = 1000 kg)
bars needed = 230000/11850 = 19.4 bars.
So you would need
20 bars to transport a minimum of 230 tonnes of steel.
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5.
DENSITY and the particle model
- explaining the relative densities of gases, liquids and solids
The density of a material depends on the
nature of the material eg air, water, wood or iron AND the physical state of
the material, which is how the particles are arranged.
In a closed system, when a
substance changes state, it is a physical change (NOT
chemical), there is no change in mass (same number of
particles), but there is a change in particle arrangement which
leads to a change in density.
We can use the
particle model of matter to partly explain the differences in density
between different materials, and in particular the difference in density
between gaseous, liquid and solid state of specific substance.
When
explaining different density values, you must consider both the kinetic
energy of the particles and the arrangement of the particles.
Applying the particle model to the different densities of the states of matter
GASES:
The particles have kinetic energy and can move
around at random quite freely.
This enables the particles to spread out and fill
all the available space giving a material a very low density compared to liquids
and solids.
With very weak intermolecular forces (NOT chemical bonds) of attraction between the particles there is
no constraint on their movement - they can't club together to form a liquid or
solid.
In a substance like air, the particles are
very widely spread out in the atmosphere giving air a very low density.
Density of air in the atmosphere is 1.2
kg/m3.
Density of steam = 0.6 kg/m3.
Hydrogen and helium are the 'lightest',
lowest density gases, ρ (H2)
= 0.10 kg/m3, ρ (He)
= 0.17 kg/m3
Carbon dioxide sinks in air because it is
'heavier', it has a higher density than air, density = 1.9 kg/m3
(air is 1.2).
If you compress a gas, you force the
molecules closer together, same mass in smaller volume, so the density
increases.
If you heat a gas and it can expand, the
particles are further apart and the density will decrease.
LIQUIDS:
In liquids, the particles are close together, usually giving
high densities a bit less than the solid, but have a much greater than the
density of gases, but the particles are NOT in a fixed close packed
ordered state as in solids..
The inter-molecular forces between liquid particles are much greater
than those between gaseous particles and are strong enough, so they
are attracted close together, with enough kinetic energy to just
leave a little free space.
The
random movement creates a little free space and on average are spaced out just
that little bit more than in solids, hence their slightly lower
density than the solid - water is a very rare exception to this rule.
Water has a density of 1000 kg/m3,
more than 1600 times more dense than steam!
Density of liquid air is 974 kg/m3,
see this sharply contrasts with gaseous air, which is over 800 times less
dense at 1.2 kg/m3!
Hydrocarbon petroleum oil, typically has
a density of 820 kg/m3, less dense than water, so it floats on
it!
Mercury atoms have a much greater atomic
mass than hydrogen, oxygen or carbon so liquid mercury has a density of 13
584 kg/m3, that is more than 13 times more dense than water!
If you heat a liquid, increasing its
temperature, the particles gain kinetic energy and the collisions become
more frequent and energetic and this enables the particles on average to
spread out a bit more, increasing the liquid volume and lowering the
density.
This effect is used in liquid
thermometers e.g. those containing a capillary tube of mercury or
coloured alcohol.
The thermal expansion is proportional
to temperature so you can fit a calibrated linear scale next to the
capillary tube.
SOLIDS:
The strongest interparticle forces of attraction occur in solids where particles
are attracted and compacted as much as is possible.
The particles are packed tightly together in an ordered array -
giving maximum density.
In small molecules - covalent compounds it is intermolecular
bonding, strong covalent bonds in giant covalent structures. Metals have strong
chemical bonds between the atoms and similar very strong bonds between ions in
ionic compounds.
The particles can only
vibrate around fixed positions in the structure and do not have sufficient
kinetic energy to overcome the binding forces and break free and move around
creating a little space as in
liquids.
The result is the highest density for the state of a specific material.
Although liquid densities for a specific material are just a bit less than those
of the solid, both the solid and liquid states have much greater densities than
the gaseous or vapour state.
Generally speaking the solid state
exhibits the highest density, particularly metals.
In a very dense material like iron, the
particles (iron atoms) are not only heavy, but very close together giving
the high density of 7870 kg/m3.
Because of the particular crystal
structure of ice (ρ
= 931 kg/m3), solid water is less dense than liquid water (ρ
= 1000 kg/m3), so ice floats on water! Very unusual! In the solid
the water molecules form a very open crystal structure in which the water
molecules are actually slightly further apart on average compared to their
compactness in liquid water.
When dealing with insulating materials,
beware!, their densities are much lower than the 'bulk' solid because very
low density gases like air or carbon dioxide are trapped in them,
considerably lowering the overall density of the original solid material.
If you heat a solid, increasing its
temperature, the particles gain kinetic energy and the vibrations become
more energetic and this enables the particles on average to spread out a bit
more ('pushing' each other apart), increasing the solid volume and lowering
the density.
See
chemistry notes on chemical bonding
Density also mentioned in
Pressure & upthrust in liquids, density,
why
objects float/sink?
TOP OF PAGE and
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6. The relative density of the liquid and
solid state and the curious case of water
Before discussing the structure of
ice we need to look at the anomalous density behaviour of water.
Left graph -
density versus temperature
for a typical liquid:
(1)
Increase in temperature of solid, increase in thermal vibration,
molecules move increasing a little more apart, density falls.
(2)
Melting occurs when intermolecular forces weakened and increased freedom of movement moves the molecules
a little bit apart decreasing the density.
(3)
Increasing the temperature increases the KE of the liquid molecules,
more energetic collisions, increasing with increase in temperature,
steadily lowers the density of the liquid as the molecules bash each
other a bit further apart as the intermolecular forces weaken more.
All of this is normal
expected behaviour.
Right graph -density
versus temperature for water:
You also need to
refer to the diagrams of ice structure below, as well as the graph above.
GCSE physics students do NOT have to
know the details of hydrogen bonding mentioned on the ice diagrams.
BUT know its the strongest type of
intermolecular force, which you do have to know about in chemistry.
Its the same intermolecular forces
that holds the double helix together in DNA and RNA, and partly
responsible for holding together the specific 3D protein shape of
enzymes - you know more about hydrogen bonding than you think!
(1)
Increase in temperature of solid, increase in thermal vibration,
molecules move increasing a little more apart, density of ice falls
- normal behaviour.
(2)
Ice melts, but instead of an expected decrease in density, you get an increase
in density of liquid water compared to ice - anomalous behaviour.
This is due to the partial breakdown of the open crystal
structure of ice and the liquid molecules, despite their greater KE
of movement,
they actually have the freedom to get closer together (about 10%
less volume) and so the density increases - you need to use a little imagination
when looking at the ice diagrams - imagine when the open crystal
structure breaks down, the water molecules can actually get closer
together.
(3a-b)
From 0oC to 100oC there is a continuous
breakdown of the 'ice-like' structures in liquid water.
YES! the ice structure does not completely break down at 0oC
on melting.
Clumps of water molecules persist and gradually get
broken down with increase in temperature - increase in KE of
molecules.
At the same time normal thermal expansion is going on!
From 0oC to 4oC the effect of ice structure
breakdown outweighs the normal thermal expansion, so you get a 2nd anomaly of the maximum density at 4oC
(just over 1.0 g/cm3 or 1000 kg/m3).
(3b) The maximum density at 4oC
is because the breakdown of ice-like structures in liquid water is
exactly balanced by the effect of normal thermal expansion.
(3c)
From 4oC the increasing KE of the molecules and more
energetic collisions outweighs the break down of the
clumps of water molecules and normal thermal expansion takes place.

ice diagram (i) |

ice diagram (ii) |
An important 'biological'
consequence of
the
curious density behaviour of water
The anomalous density behaviour
of ice has really important implications for aquatic life.
Because ice forms and floats on
the surface of water, life can go on as normal in the liquid water below the ice.
The ice actually provides some
insulation from the cold atmosphere, and in deeper ponds, rivers and
lakes, most aquatic life can go on as normal.
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7. Thermal expansion and density
The vast majority of materials expand on heating,
whether they be gases, liquids or solids.
In the case of solids, raising the temperature
increase the internal energy in the form of increased thermal
vibration of the atoms.
The increased amplitude of vibration of the
particles causes them to be forced further apart, an effect we call
thermal expansion.
Different materials expand at different rates with
increase in temperature.
This effect is made use of in a bimetallic strip
- illustrated below.
Different metals expand different amounts for the same temperature rise.
A bimetallic strip is made from two different metals joined together.
The effect of heating a bimetallic strip is shown in the diagram.
The table below shows the length increase in mm on heating 2 metre
(2000 mm) strips of the metals by 10oC. [8i-94]
METAL |
aluminium |
brass |
copper |
steel |
length increase |
0.49 |
0.40 |
0.25 |
0.22 |
Suggest a pair of metals that were was used in the experiment illustrated?
Metal B must expand more than metal A
e.g. Metal B could be brass and metal A could be
steel.
Uses of
bimetallic strips
A change in temperature triggers some kind of physical effect to
control a situation.
e.g. bimetal
strips are also used in gas oven safety valves and thermostat
controls.
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UK KS3 Science Quizzes for
students aged ~11-14, ~US grades 6 to 8
Biology * Chemistry
* Physics notes for GCSE/IGCSE
students aged ~14-16, ~US grades 9 to 10
Advanced Level pre-university Chemistry
revision notes for students aged ~16-18 ~US grades 11 to 12
OCR A gcse 9-1
physics P1.1d Be able to define density. From measurements of length, volume and
mass be able to calculate density. See also the investigation of
Archimedes’ Principal using eureka cans. density (kg/m3) = mass (kg)
/ volume (m3) d = m/v P1.1e Be able to explain the
differences in density between the different states of matter in terms of the
arrangements of the atoms and molecules. P1.1f Be able to apply the relationship
between density, mass and volume to changes where mass is conserved. You should
be familiar with the structure of matter and the similarities and differences
between solids, liquids and gases. You should have a simple idea of the particle
model and be able to use it to model changes in particle behaviour during
changes of state. You should be aware of the effect of temperature in the motion
and spacing of particles and an understanding that energy can be stored
internally by materials. P1.2a Be able to describe how mass is conserved when
substances melt, freeze, evaporate, condense or sublimate. Use of a data
logger to record change in state and mass at different temperatures.
Demonstration of distillation to show that mass is conserved during evaporation
and condensation. P1.2b Be able to describe that these physical changes differ
from chemical changes because the material recovers its original properties if
the change is reversed. IGCSE
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